Recovery of potassium salts and borax



UNITED STATES PATENT OFFICE.

KARL J. JACOBI, 0F ROSI ELLE PARK, NEW JERSEY. ASSIGNOR TO PACIFIC COAST BORAX COMPANY, OF NEW YORK, N. Y.. A CORPORATION OF NEVADA.

RECOVERY OF POTASSIUM SALTS AND BORAX.

No Drawing.

T 0 all whom it may ooncer'n Be it known that I, KARL J. JACOBT, a citizen of the United States, residing at Roselle Park, in the county of Union, State of New Jersey, have invented certain new and useful'lm )rovements in the ieeovery of Potassium Salts and Borax; and I do hereby declare the following to be a full, clear, and exaot desvription of the invention, such willenable o her. skilled in the art to which'it appertuins to make and use the same.

This invention relates to iniprovmnents in recovery of potassium salts and borax from brines of the ohm-actor of the Searles Luke brine.

In the treatment of these brines, as heretofore prartised, it has been customary to:

concentrate the hrines until portion of the sodiumsalts has separated therefrom am the solution has become nearly saturated with potassium salts, then to filter the concentrated brine from the separated salts, and permit the filtered brine to cool. Potassium salts made up largely of ehlorid are obtained in this Way, but it is contmninated with a very mnsideruble amount of boinx. and eorrespondingly im nere pot inn: subs are aevordingly obtained. Tlt is eustmuary then to return the brine... after sepals tion of the impure potassium there frorn, for further conventratio?i w for ndmixture with fresh amounts oi urine.

According to the present invention, the potassium salts are obtained in port in a state of high purity, and in part in the torn: of a mixture of potassium salts and bornx which is further treated for the separation of the potassium salts and bornx.

The invention will be further illustrated by the followin specific description The brine, or example, Searles Lake brine, is concentrated in an evaporator until about to per cent. of the total sodium carbonate content of the brine is separated out together with other sodium salts such Specification of Letters Patent.

Patented A 11". 10, 1920.

Application filed August 25, 1919. Serial No. 319.744.

120 F., during whieh time a vonsiderable part of the potassium salts separate out in a relatively pure form, i. 0.. relatively free from borax Potassium salts ran thus be obtained which, u'hen freed fronr'mother liquor, roui'uius :1. low percentage of borax, \vhu-h may be as little as one per cent. or less. and containing: as high as so to 94 per rent. of potassium salts rulculated as potassium rhlorid. The temperature at which the desirable result is :u'vomplished i a variable fiu'tor n'hirh depwuds upon numerous conditions; and l do not desire that the invention be limited to the speeil'ir range of temperature mentioned. H the mother liquor is permitted to rool to :l temperature Very murh below [but unlimited. Laoran will begin to separate out as weli. :uul the potas sium alts will be l s pure. Am-ordinglv, after the first separation of relatively pure potassium salts the potassium salts are filtered out and obtained in a state relatively free from horax. The mother liquor is theh transferred to another tank where it is per omitted to ruol down to ord uury temperature and in iliitil :1 separation of potassium salts and horas; takes is. re. The mixture of pr tossiurn salts and thus obtained is filtered oil and n sr puat-ly {rented for the rrrowry of the potu salts and borer; therefrom. in a zelatlvetv pure state. f. .2, h-iutirely true from envh other.

The hold mother liquor remaining after .reniovnl of the mixed rig stal is now ucidi tied with a suitable acid or acid compound, preferably hydrooblori acid, until the ulkulinity, eah'nluted sodium oxid is enough to form born); with the total amount of horie oxid present. This addition of acid results in the deeonniositiml of u "very eonsidernhle amount of rurbonute pres nt wit resulting evolution of vari 011 dioxid. Arse nio. whirh is present in :ippreriable quun' iities, is pi'eoipitut d. s result of aeidifieution. may when desired, piwfede the um sop-urn.- tion of the potassium salts.

The liquor is then again miner-minted in much the same manner as before and the concentration is continued until a considel" able portion of the remaining;- sodium salts are separated out. The reronventrated liquor after filtering from the arsenic and sodium salts, is again permitted to cool, first Aeidifiration (1S .lbme desa'ribed;

- p 'oximalt for the separation of relatively ure potassium salts, i. e., relatively free rom borax, and containing from 60 to 80 per ent. or more of potassium salts figured as potassium chlorid, the remainder being mainly sodium chlorid and other sodium salts, which potassium salts are filtered off, and then to ordinary temperatures for the separation of a further amount of mixed potassium salts and borax. The crystals of potassium salts thus separated are substantially free from borax, although they may be admixed with sodium chlorid .or other sodium salts. These crystals of potassium salts so separated can be freed from adherin mother 11 uor containing borax disso ved therein in any suitable manner.

The cold mother liquor remaining after this second concentration and crystallization can be further treated by concentration or, if it is small in amount, it can be returned to the evaporator and mixed with fresh amounts of acidifiedbrine either before or after the primary separation of potassium salts therefrom, or with the mother liqlqor from other batches of brine.

he treatment of the mother liquor with acid can be effected while the mother liquor is still hot and prior to the cooling and crystallization thereof, but this is more obectionable and requires added precautions ecause of the vigorous evolution of carbon dioxid caused by the addition of the acid to the heated liquor. It is more advantageous and economical to add the acid to the cold mother liquor, after the separation of the crystals therefrom, than to treat the ori inal brine, for the reason that a considcra le portion of the soda ash will have been eliminated during tl; e first concentration so that a correspondingly small amount of acid or acid compound is required.

The particular amount of acid or acid compound can be varied. In general, however, I pr fer and recommend adding apthe amount of aqid above referred to so that the alkalinity will correspond to that of borax, that is, so that there will be sufficient sodium oxid to form borax with the total amount of bdricaacid present. Then, upon subsequent concentration and cooling, the boric acid B 0, willbe separated out in the form of borax and in admixture with the potassium salts.

By proceedin in the manner above described there is o )tained, first, relatively pure potassium salts relatively free from )orax,

Qand, thereafter, mixed crystals of potassium salts and borax well adapted for subsequent treatment for the recovery of potash and borax therefrom. If, however,the alkalinity,

after the addition of the hydrochloric acid, is not regulated in the manner descril'ied. the borax may be admixed with other b01'llt( 3S,'QI with boric acid.

Instead of hydrochloric acid, other acids or acid compounds can be likewise employed, with corresponding modification of the process; but hydrochloric acid is well adapted for use and is to be recommended even though it is somewhat more expensive than sulfuric acid.

The mixed crystals obtained, as above described, contain much more borax than p0- tassium salts; the amount of borax may be as much as two times the amount of potassium salts.

In order to effect the separation of the potassium salts from the borax the mixed crystals are dissolved in hot water and made into a solution of such a strength that, on crystallization of borax by cooling, no appreciable amount of potassium salts will separate out. That is, the solution should not be saturated with potassium saltswhile' separation of orax therefrom in a substantially pure state. As much as 85 per cent. or more of the borax may be thus removed, with the resulting production of a solution or mother liquor much richer in potassium salts than it is in borax.

The separated borax is filtered off and the mother liquor again evaporated until potassium salts in large quantities have separated out during the evaporation. These potassium salts separate in a relatively pure state i. e., relatively free from borax and are filtered off while hot. The mother liquor is then permitted to cool and a further amount of potassium salts is so arated therefrom at temperatures preferalily above 150 to 130, but depending upon the composition of the solution. As hereinbe fore noted the temperature ran 8 stated is subject to variation and is not t erefore to be taken as a limitation of the invention. These potassium salts are then filtered off, and the solution further cooled, whereupon a crop ofmixed crystals potassium salts and borax is obtained. That is, the concentration and cooling of the liquor gives relatively pure potassium salts 1f the cooling is stoppe at the proper temperature, and thereafter, the potassium salts are obtained in admixture with borax in the form of mixed crystals which can be used asthe,

The liquor remaining after the first separation of borax, potassium salts and mixed crystals, instead of being reconcentrated, can be used to dissolve further amounts of mixed crystals in a heated state and the resulting solution subjected to the same general procedure outlined above for the recovery of borax and potassium salts, both relatively pure, and for the subsequent recovery of mixed crystals which can be added to other like mixtures for sin plar treatment.

As a result of the. improvements of the present invention, the potassium salts and borax can be obtained in high state of purity and ready for the market, while mixed crystals can be obtained in a form Well adapted for further treatment for the sepa ration of merchantable potassium salts and borax therefrom. The method as herein described is particularly advantageous because of the relatively large quantity of borax in a substantially pure condition which is thcrcby recovered.

While the various steps of the process, including the preliminary preparation of the mixed crystals. and the subsequent treat ment thereof for the separation of potas sium salts and borax. areadvant igeously combined as a part of the same process, nevertheless. certain of these steps are capable of more general application. and ,may be separately used or combined With other steps varying from those above described. 'lhc mixed crystals may, for example, be prepared and snipped to another place of treatment or of use. So, also, mixed crystals produced otherwise than by the specific process above described can be separated into relatively pure potassium salts and borax by the separation steps of the process of the present invention. Impur potas sium salts. containing admixed borax, pro duced by prior processes, can thus be treated, according to the present invention, for the separation of potassium salts and loorax of liiub purity therefrom.

I claim:

l. The method of recovering potassium salts and borax from alkaline hrines containing sodium salts, which comprises concentrating thc brines to remove a considerable portion of the sodium salts, coolin Y the cum'i'lltlulwl brincs for the recovery tierefrom. first. of potassium salts relatively free from borax and. second, of mixed potassium and borax curstulsJ acidifying the cold mollicr liquor to remove a portion of the alkalinity. and further concentrating and cooliu; thc resulting: solution for the HUPEF ration of sodium salts. of relatively pure potassium salts. and of mixed crystals of potassium salts and borax, therefrom; suhslauliully as described.

2. 'llumethod of recovering potassium salts and borax from brines containing sodium salts, which comprises concentrating the lirines to remove a considerable portion of the sodium salts, subjecting the concen- [rated brine lo a twostage cooling opera tion, first, to separate therefrom potassium salts relatively free from borax and. second, at a lower temperature, to separate mixed crystals of potassium salts and borax, aciditying the mother liquor with hydrochloric acid until its alkalinity calculated as sodium oxid is about enough to form borax with the total amount of boric 'oxid present, again concentrating the liquor, and again cooling; it for the preparation of further amounts of potassium salts and borax therefrom; substantially as described.

3. The method of recovering potassium salts and borax from brincs containing them. which comprises concentrating the brine. until it is saturated or nearly saturated in potassium salts, cooling, the brine to s parate potassium relatively free from borax bcl'orc the separation of borax. separating the crystallized potassium salts and further cooling the luinc'to separate a mixture of potassium salts and borax; substantially as described.

4;. The method of recovering potassium salts and borax from concentrated brines containing the same, which comprises subjccting thebrine to a two-stage cooling operation, first, to separate potassium salts substantially free from burns, and, second. to separate a mixturc of potassium salts and borax. and separately collecting the potassium salts and the n'iixed crystals; substantially as described.

3. The method of recovering potassium salts and borax from brincs ol the character of Hearles Lake brine. which comprises concentrating the brine to remove a considen able portion of the sodium salts. cooling the concentrated brines for the separation of potassium salts and borax therefrom, acidifying the cold mother liquor to reduce its alkalinity. concentrating, the resulting solution for the separation of further amounts of sodium salts, and cooling the concern trated liquor for the recovery of further amounts of potassium salts and borax; sub stantially as described.

(3. The method of improving the recovery of potassium salts and borux from alkaline brines containing them, which comprises acidifying the brine to reduce its alkalinity, concentrating the resulting brine and cooling the concentrated brine, substantially as described.

7. The method of recovering potassium salts and borax from alkaline brines contuining sodium salts, which comprises adding hydrochloric acid until the alkalinity calculated as sodium oxid is approximately such as to form bomx with the total amount of 'lJOIiiC oxid present, concentrating the resulting liquor, and coolin the concentrated liquor for the recovery 0 potash and borax therefrom; substantially as described.

8. The method of recovering potassium salts and borax from brines containing sodium salts, which comprises concentrating the brine for the separation therefrom of a considerable portion of the sodium salts, cooling the concentrated brine in two succes sive stages and thereby separating, first, otas sium salts relatively free from borax, ant. thereafter, a mixture of potassium salts and borax containing an excess of borax, dis solving the separated mixed crystals to form a hot solution from which no appreciable amount of potassium salts will separate when cold, cooling the solution for the separation of borax therefrom, and concentrating the remaining liquor for the separation of potassium salts therefrom; substantially as described.

9. The method of recovering potassium salts and borax from mixed crystals containing an excess of borax, which comprises dissolving the mixed crystals in hot water or a hot aqueous liquor to form a solution nearly saturated with potassium salts when cold, cooling the solution for the separation of borax therefrom, and concentrating the resulting liquor to effect the separation of potassium salts therefrom; substantially as described.

10. The method of recovering potassium salts and borax from mixed crystals containing an excess of borax which comprises dissolving the mixed crystals in hot water or a hot aqueous liquor to form a solution nearly saturated with potassium salts when cold, cooling the liquor to separate borax therefrom, concentrating the resulting liquor to recover potassium salts therefrom, and subsequently cooling to obtain further amounts of potassuim salts and borax therefrom; substantially as described.

11. The method of recovering potassium salts and borax from brines of the character of Searles Lake brine, which comprises concentrating the brine to remove a considerable portion of the sodium salts, cooling the concentrated brine in two successive stages, first, to a temperature of about 115 to 130 C. for the separation of potassium salts therefrom relatively free from borax, and thereafter, to a lower tem erature for the separation of a mixture 0 potassium salts and borax; substantiall as described.

12. In the recovery 0 potassium salts and borax from alkaline brines containing them, the improvement which comprises acidifying the brine to reduce its alkalinity until its alkalinity, calculated as sodium oxid, is about enough to form borax with the total amount of boric oxid present, and thereafter separating potassium salts and borax from the thus neutralized brine; substantially as described.

13. The method of recovering potassium salts and borax from alkaline brines containing sodium salts, which comprises con-' centrating'the brine to remove a considerable portion of the sodium salts therefrom, acidifying the brine until its alkalinity, calculated as sodium oxid, is about enou h to form borax with the total amount of lioric oxid present, and thereafter separating potassium salts and borax from the brine; substantially as described.

14. The method of recovering potassium salts and borax from solutions containing an excess of potassium salts, which comprises concentrating such solution to effect separation of potassium salts therefrom without separation of borax, separating the potassium salts, and cooling the brine to separate further amounts of a mixture of potassium salts, and borax; substantially as described.

15. The method of recovering potassium KARL .1. JACOBL free from borax; sub- 

